The invention relates to universal joints. More particularly the invention relates to tripod constant velocity universal joints.
Front wheel drive vehicles with independent front wheel suspension use a pair of halfshaft assemblies to transmit power between the vehicle's engine and the front wheels.
Typically these halfshaft assemblies comprise a fixed joint at one end and a plunging joint at the opposite end. These joints are connected by an interconnecting shaft.
The fixed joint is typically positioned at the wheel side of the vehicle. These joints are deigned to high angle (45.degree.-50.degree.) operation. The fixed joints allow the vehicles front wheels to turn in order for the vehicle to negotiate corners. The center of angulation of the fixed joints is constant.
The plunging joint is typically positioned at the transmission or transaxle side of the vehicle. These joints are designed for lower angulation (20.degree.-25.degree.). The center of angulation of these joints is not fixed but is allowed to move axially (plunge) along the axial center line of the joints outer member. This capability of angulation and plunge movement allow the joint to transmit power while at the same time accommodating suspension and engine movement.
A tripod joint is one design of a plunging constant velocity joint. A tripod joint comprises an outer member with three circumferentially spaced longitudinal chambers. Disposed within these chambers is a spider assembly. The spider assembly comprises an inner member with three circumferentially spaced radially extending trunnions. Each trunnion is surrounded by a roller. A plurality of needle bearings are journaled between the roller and the trunnion. This permits free rolling of the roller on the trunnion. The outer surface of the roller is in contact with the sides of the longitudinal chambers of the outer member.
When the tripod joint is at a 0.degree. angle, the plunging effort is relatively low. The roller rolls against the longitudinal chamber of the outer member and rotates on the trunnion of the inner member using the plurality of needle bearings.
When the tripod joint is operated at an angle, the tripod roller is not free to roll along the track because the plane of the tripod roller is skewed relative to the plane of the outer member's chamber. This skewed relationship causes the roller to both roll and slide along the longitudinal chamber. As the joint angle increases, the amount of sliding also increases.
The sliding action of the roller against the longitudinal chamber causes a third order axial vibration which is known as shudder. As the angle of the joint increases, the sliding action increases and thus the shudder increases. Depending upon the vehicles design, this shudder vibration can become noticeable and objectionable to the people riding in the vehicle.
One method of reducing this shudder phenomenon is to separate the components within the joint which have the responsibility for allowing the joint to go to angle from those which allow the joint to plunge. If the plane of the roller is allowed to remain substantially in the plane of the longitudinal chamber, the sliding of the roller during plunging of the joint would be minimized. With the sliding of the roller with respect to the longitudinal chamber minimized, the shudder phenomenon would be reduced.
Accordingly it is desirous to have a tripod joint assembly with internal components which separate the responsibility of providing angular and plunging movement of the tripod joint.